RDS Group Research Articles

Evaluation of thalamus echogenicity via ultrasonography as a marker of fetal lung maturity

Background: Fetal lung immaturity is a major problem in the management of elective birth with respect to predicting the development of infant respiratory distress syndrome (IRDS) in the neonate after birth.Aim and Objectives: The aim of this study was to evaluate the validity of measuring fetal thalamic echogenicity by ultrasound as a marker of fetal lung maturity.Subjects and Methods: This was a prospective observational study that was being carried out on 80 pregnant patients. They were recruited from Obstetrics and Gynaecology clinics at Tanta University Hospitals during the period of research from March 2021 till the end of the study.Results: There was statistically significant difference between RDS group and those without RDS regarding thalamic echogenicity, 1 and 5- min APGAR score, NICU admission and neonatal mortality.Conclusion: Evaluation of echogenic thalamus by ultrasound at the level of the BPD is of value, and can be considered as a new marker of fetal lung maturity; however, further studies are required to strengthen such idea.

Evaluation of thalamus echogenicity via ultrasonography as a marker of fetal lung maturity

Background: Fetal lung immaturity is a major problem in the management of elective birth with respect to predicting the development of infant respiratory distress syndrome (IRDS) in the neonate after birth.Aim and Objectives: The aim of this study was to evaluate the validity of measuring fetal thalamic echogenicity by ultrasound as a marker of fetal lung maturity.Subjects and Methods: This was a prospective observational study that was being carried out on 80 pregnant patients. They were recruited from Obstetrics and Gynaecology clinics at Tanta University Hospitals during the period of research from March 2021 till the end of the study.Results: There was statistically significant difference between RDS group and those without RDS regarding thalamic echogenicity, 1 and 5- min APGAR score, NICU admission and neonatal mortality.Conclusion: Evaluation of echogenic thalamus by ultrasound at the level of the BPD is of value, and can be considered as a new marker of fetal lung maturity; however, further studies are required to strengthen such idea.

Perinatal predictors and ultrasound diagnostics of newborn respiratory disorders

Respiratory distress is one of the most common causes of neonatal morbidity and mortality. The aim of this study was to determine perinatal factors and ultrasonographic features of newborn respiratory disorders. We examined 49 children aged 0-28 days who had manifestations of type 1 RDS (group 1 – 24 children) and pneumonia caused by intrauterine infection or massive meconium aspiration syndrome (group 2 – 25 children). The control group consisted of 20 newborn. The control group consisted of 20 newborns. Data analysis showed that the presence of extra genital pathology that had mother, significantly influenced on the development of respiratory disorders (group 1 – 75 % ,and group 2 – 60 % compared to the control group – 20 %), as well as a high frequency of chronic fetal hypoxia and placental dysfunction complicated by fetal distress (in group 1 – 75 % of cases, in group 2 – 40 %) It was found that ultrasound examination of the lungs is an informative, safe method for diagnosing pneumonia, pneumothorax, the presence of fluid in the pleural cavity of newborn respiratory disorders, and provides an opportunity to monitor pathological changes during treatment.

Measurement of tidal respiration in

Objective To investigate pulmonary function in terms of tidal respiration and the influencing factors on it in <34 weeks premature infants with RDS at corrected gestational age of 40 weeks. Methods A total of 49 of <34 weeks premature infants with RDS (RDS group) and 36 of <34 weeks premature infants without RDS (non-RDS group) followed throughout entire twelve months were collected from December 2013 to October 2015.Of them, 35 RDS patients and 20 non-RDS patients had the pulmonary function examination .A total of 26 full term infants with hyperbilirubinemia (full term group) were recruited for comparison study. The differences in parameters of tidal respiration were compared among the three groups. The RDS patients were further divided into the mild RDS subgroup and severe RDS subgroup according to the severity of illness. Result ①The TPEF [(0.17±0.04)s vs.(0.23±0.09)s], VPEF [(6.74±2.70)mL vs.(9.33±2.92)mL], TPEF/TE [(29.06±4.21)% vs. (38.27±7.16)%], VPEF/VE [(32.54±4.43)% vs. (39.64±5.88)%] in RDS group were significantly lower than those in full term group (P 0.05). ②The TPEF, VPEF, TPEF/TE, VPEF/VE in mild RDS group were higher than those in severe RDS group, but the differences were not significant (P>0.05). ③Logistic regression analysis indicated that the gestational age was the protective factor of pulmonary function in premature infants with RDS. Conclusions Small airway resistance in <34 weeks premature infants with RDS is higher than that in full term infants. There was no significant difference in pulmonary function between RDS premature infants and non-RDS premature infants. The gestational age was the influencing factor of pulmonary function in premature infants with RDS. Key words: Respiratory distress syndrome; Premature infant; Full term infant; Newborn; Tidal respiration pulmonary function; Mild; Severe; Influencing factors

Chondrocyte Cell-Sheet Transplantation for Treating Monoiodoacetate-Induced Arthritis in Rats.

Engineered cell sheets that are fabricated by using temperature-responsive culture dishes are now available in the clinical setting. Engineered chondrocyte cell sheets are used in clinical trials for treating focal articular cartilage defects. However, the efficacy of engineered chondrocyte cell sheets for treating diffusely degenerated articular cartilage remains unknown. In the present study, we assessed the utility of engineered chondrocyte cell sheets for treating diffusely degenerated articular cartilage in a monoiodoacetate (MIA)-induced arthritis animal model. At 1 and 3 weeks after intra-articular MIA injection into rat knees (1 w-MIA/3 w-MIA model), the degenerated cartilage at load-bearing area sized 1 × 3 mm was removed. Rats in each group were divided into three subgroups: Removal (R) group as control, Removal + Drilling (RD) group in which cartilage was removed followed by subchondral drilling, and Removal + Drilling + Sheet transplantation (RDS) group in which the removed cartilage area was covered with a 2 × 4 mm size of triple-layered chondrocyte cell sheet. In the histological assessment, the score of the RDS group in each model was significantly better than that of R and RD groups at 4 and 12 weeks, respectively, after the surgery. Our results demonstrated that the transplanted chondrocyte cell sheets improved cartilage repair even under such severe conditions as diffusely degenerated articular cartilage. Chondrocyte cell sheets appear to be useful as a treatment option for MIA-induced arthritis models.

Association between Interleukin-10-1082 G/A and Tumor Necrosis Factor-α308 G/A Gene Polymorphisms and Respiratory Distress Syndrome in Iranian Preterm Infants

Cytokine polymorphisms may contribute to the prevalence of respiratory distress syndrome. The present study was done to investigate the frequency of interleukin- (IL-) 10 and tumor necrosis factor- (TNF-) α gene polymorphisms and their association with the risk of RDS in preterm infants. One-hundred and nineteen patients with RDS and 119 healthy preterm infants were enrolled. PCR restriction fragment length polymorphism was used to determine the frequency of IL-10 and TNF-α genotypes at -1082 A and -308 A, respectively. One-hundred and nineteen out of 238 infants had RDS (50%). The age of the mothers and gestational age ranged 17–45 (mean: 28.6 ± 5.3) years and 24–34 (mean: 34.3 ± 2.38) weeks, respectively. Totally, 23 deaths were recorded in the RDS group. Incidence of TNF-α-308 A/A and TNF-α-308 G/A was 84% and 16%, respectively. TNF-a-308 G/G was not found in both groups. Prevalence of IL-10-1082 G/G and IL-10-1082 G/A variants was 65.5% and 34.5%, respectively. IL-10-1082 A/A was not found in both groups. The incidence of the allele G in the IL-10-1082 polymorphism was lower in RDS group (P < 0.05). We found that the risk of RDS was correlated to sex, gestational age, and IL-10-1082.

Should fetal scalp blood sampling be performed in the case of meconium-stained amniotic fluid?

Objective: To investigate the effect of using fetal scalp blood sampling on the risk of neonatal respiratory distress syndrome (NRDS) with meconium-stained amniotic fluid (MSAF).Methods: Prospective data collection with regard to MSAF during labor for low-risk term cephalic singleton live birth from 2012 to 2014. Maternal, obstetric and neonatal data were compared according to the occurrence of respiratory distress syndrome (RDS group) or not (no RDS group).Results: Of 515 newborns born through MSAF, 46 experienced RDS and from them 10 experienced meconium aspiration syndrome. No difference was observed according to maternal characteristic, abnormal fetal heart rate tracing pattern irrespective of its category and cesarean rate. Apgar at one minute was lower in the group RDS (7.6 versus 8.5, p < 0.05). The mean umbilical artery pH values did not differ between the two groups. Significant difference between newborns with and without RDS in terms of fetal scalp lactate sampling during the labor (71.1% versus 55.1%, p < 0.05), and neonatal care unit (NCU) admissions (22.8% versus 10.8%, p < 0.05). Secondary rather than primary meconium was associated with RDS when performing fetal scalp blood assessment (p < 0.05). A significant correlation between RDS, fetal scalp blood assessment and MSAF diagnosed during the first stage of labor (after spontaneous rupture of membranes or at amniotomy) was found.Conclusion: In case of MSAF, fetal scalp blood sampling did not reduce the risk of RDS.

PF.49 Term Admissions to the Neonatal Unit; Are They Avoidable?

IntroductionApproximately 10% of all babies born require admission to the neonatal unit and term infant represent a significant percentage of NICU admission and are major contributors to workload.AimTo identify potentially...

Frequency Modulation and Spatiotemporal Stability of the sCPG in Preterm Infants with RDS

The nonnutritive suck (NNS) is an observable and accessible motor behavior which is often used to make inference about brain development and pre-feeding skill in preterm and term infants. The purpose of this study was to model NNS burst compression pressure dynamics in the frequency and time domain among two groups of preterm infants, including those with respiratory distress syndrome (RDS, N = 15) and 17 healthy controls. Digitized samples of NNS compression pressure waveforms recorded at a 1-week interval were collected 15 minutes prior to a scheduled feed. Regression analysis and ANOVA revealed that healthy preterm infants produced longer NNS bursts and the mean burst initiation cycle frequencies were higher when compared to the RDS group. Moreover, the initial 5 cycles of the NNS burst manifest a frequency modulated (FM) segment which is a significant feature of the suck central pattern generator (sCPG), and differentially expressed in healthy and RDS infants. The NNS burst structure revealed significantly lower spatiotemporal index values for control versus RDS preterm infants during FM, and provides additional information on the microstructure of the sCPG which may be used to gauge the developmental status and progression of oromotor control systems among these fragile infants.

Role of Protein Z and Protein C in Neonates with Respiratory Distress Syndrome in Egypt (Experience of One Centre)

The aim of this study is to evaluate Protein Z (PTZ) and protein C (PTC) levels in newborns suffering from RDS, healthy preterm and full term newborns and to compare PTZ serum levels in RDS preterm infants with healthy preterm before and after recovery. Sixty newborn infants, recruited from the neonatal unit, were enrolled in the study and divided into 3 groups: Group (I): 20 preterm with RDS, Group (II): 20 healthy preterm control newborns (CPT) and Group (III): 20 healthy full term control newborns (CFT). Protein Z and C were measured using ELISA kits. The results of the study showed lower levels of protein Z were obtained in RDS group compared to preterm controls whose levels were significantly lower than in full-term controls. A significant increase in PTZ levels in RDS' group after recovery, when compared to preterm controls. In RDS, no significant correlations existed between PTZ levels (before and after recovery) and routine investigations except for a significant negative correlation with platelets count. No significant differences were found in PTC levels between the 3 studied groups. To conclude: premature newborns suffering from RDS showed decreased serum protein Z levels than normal preterm control newborns with further increase in its pattern after recovery. Further studies are recommended to evaluate the role of PTZ on outcome in premature newborns with RDS and to evaluate the relationship between protein PTZ and PTC and other coagulation factors incriminated in the development of RDS.

Effect of exogenous surfactant therapy on levels of pulmonary surfactant proteins A and D in preterm infants with respiratory distress syndrome

To examine whether exogenous pulmonary surfactants (exPS) substitute for or merely supplement endogenous pulmonary surfactants (enPS) by looking at sequential changes in the surfactant proteins (SP) SP-A and SP-D in alveolar pools. Fourteen preterm infants with RDS treated with an artificial surfactant were compared to five normal-term infants without RDS who were treated with artificial ventilation at birth. Immediately after birth, SP-A and SP-D were essentially absent in the alveolar pools of the RDS group, but were present at normal levels in the controls. Treatment with exPS apparently stimulated enPS production. In infants who responded well to exPS therapy, the SP concentration reached essentially normal levels within 48-72 h after birth.

Cord blood IL-10, IL-12 in preterm newborns as predictors of respiratory distress syndrome and bronchopulmonary dysplasia

Purpose : Inflammation plays a major role in the pathogenesis of RDS and BPD in the immature lung. We investigated the possible role of IL-10 and IL-12 in the cord blood of preterm newborns with RDS or BPD. Methods : Forty preterm newborns whose mothers received antenatal care at Ewha Womans University Mokdong Hospital between January 2003 to June 2005, and agreed to testing their cord blood samples were enrolled. The gestational ages were below 34 weeks. Cord blood level of IL-10 and IL-12 were determined by ELISA. We separated the patients into 2 groups (RDS group and non- RDS group, BPD group and non-BPD group) and compared the cytokine levels and clinical records of the groups. Results : Cord blood IL-10 level showed a significant inverse correlation with gestational age and birth weight (P=0.001, P=0.005). Preterm infants with RDS showed higher IL-10 level (1.0 vs 0.1 pg/mL; P=0.001) in the cord blood than those without RDS. The differences remained statistically significant after correction for the effect of gestational age between both preterm groups. Despite similar cord blood IL-10 levels, preterm infants with BPD showed no significant difference with those without BPD. Conclusion : Cord blood IL-10 levels are increased in preterm infants which may be due to the immuno-suppression occurring during pregnancy and to fetal immaturity because these levels are inversely correlated with the gestational age. So, Cord blood IL-10 level can be used as the predictor of RDS.

P19Evaluation of fetal lung maturity by the gray level histogram width

Maeda has normalized gray level histogram width (GLHW) of fetal lung and liver. The fetal lung GLHW was less than 30% and smaller than the liver in 24–29 weeks. However the fetal lung GLHW was similar to the liver and over 30% after 30 weeks. We suggest this change of GLHW have relation to fetal lung maturity.MethodThe histogram was described with Aloka SSD‐1200, the 1250pixels were set at fetal lung and liver. GLHW is obtained by the histogram base length is divided by the full gray scale length. The 10 fetuses lung and liver were recorded in 24–31 weeks, and amniotic fluid samplings by transvaginal or amniocentesis were examined microbubble test. They were delivered during 1–3 days later, we diagnosed RDS or nonRDS by clinically.ResultThe GLHW of fetal lung/liver was 32.45/34.03 in 5 fetuses less than 10 microbubble rate and nonRDS (Group 1), no significant difference. The GLHW of fetal lung/liver was 30.23/34.44 in 5 fetuses over 10 microbubble rate and RDS (Group 2), significant difference (PÅÅ0.016). The fetal lung GLHW was no significant difference in group 1 and 2 (32.45/30.23) (P = 0.064), however, in the over 30 fetal lung GLHW, 5 were nonRDS and 2 were RDS, in less than 30 fetal lung GLHW, all are RDS, significant difference (P = 0.04).ConclusionThe fetus of fetal lung GLHW is smaller than liver and less than 30 is almost RDS, the case of fetal lung GLHW is larger than liver and over 30 is almost nonRDS.

F101Evaluation of a new and noninvasive method for determination of fetal lung maturity and risk to RDS

Based on our observations in humans (AJOG 1999; 180:s86) that fetal breathing movements (FBMS) are associated progressively with nasal fluid flow velocity waveforms (NFFVW) as the fetus matures, we now assess this phenomenon relative to the development of neonatal RDS. In effect, we present the possibility that evaluation of FBMS by M‐mode US with simultaneous determination of NFFVW by Doppler flow analysis, may permit diagnosis of fetal lung maturity (FLM) and, thus, risk to NRDS by rapid and reliable noninvasive methods. To the purpose of the study, the FBMS and the NFFVW data were compared with conventional data from amniotic fluid (AF). 39 high‐risk pregnancies were enrolled; all babies were delivered by CS within a week. Each fetus was surveyed for 30 min for thoracic movements (TM), indicative of regular FBMS, by M‐mode and at the same time for NFFVW. Amniocentesis was then performed. The AF sample was analyzed for L/S, lamellar bodies and presence of PG. Of the 39 pregnancies studied, 25 of the neonates had no RDS. Of the latter, only 3 registered no FBMS and NFFVW in utero; they also failed each of the AF tests, while 2 registered only FBMS and equivocal AF tests. 14 neonates developed RDS and none registered NFFVW in utero and each failed the AF tests for FLM. Only 2 of the RDS group had no FBMS. The study indicates that the presence of both FBMS and NFFVW indicates no risk to RDS. Absence of NFFVW, with or without FBMS, has the opposite connotation. The diagnostic accuracy of the noninvasive tests was: sensitivity, 100%; NPV (‘no‐RDS’), 100%; specificity, 80% and PPV (‘RDS’), 73%. The results strongly encourage further evaluation of the noninvasive methods as reliable approaches for evaluating FLM, particularly in cases where af sampling is undesirable or impossible (Supported by EURAIL, Europe Against Immature Lung).

Indications of Coagulation and/or Fibrinolytic System Activation in Healthy and Sick Very-Low-Birth-Weight Neonates

A combined hemostatic defect consisting of a reduction in certain procoagulants, anticoagulants (antithrombin III-ATIII-, protein C-PC-) and components of the fibrinolytic system (plasminogen-Plg-) was demonstrated in very-low-birth-weight infants (VLBW <1,500 g) with gestational age 26–32 weeks. Sixteen of them were healthy, 28 were suffering from RDS and 24 from septicemia. The hemostatic defect was more profound in the RDS group, nevertheless increased TAT (thrombin + ATIII complex) and/or PAP values (plasmin + a₂-antiplasmin complex) was a more frequent finding in the septicemic group of infants (91.8 vs. 17.9%). Moderate-to-severe thrombocytopenia was detected in a higher percentage in the septicemic (70.8%) than in the RDS group (50%), and increased D-dimers were demonstrated in 34.8 and 28.6% of the infants, respectively. Elevated TAT or PAP values were not always associated with gross coagulation abnormalities, and advanced disseminated intravascular coagulation (DIC) was only documented in 16.7% of the septicemic and 7.1% of the RDS infants. None of the VLBW neonates presented with clinical evidence of thrombosis, although hemorrhagic manifestations were apparent in 34.8 and 14.3% of the neonates with septicemia or RDS, respectively, mainly due to DIC or severe thrombocytopenia. In conclusion, increased TAT and/or PAP values are good indicators of the in vivo activation of the hemostatic system, but still their impact on sick neonates morbidity and mortality remains unknown.

THYROID HORMONES AND PROLACTIN IN PREMATURE INFANTS WITH AND WITHOUT RDS AFTER PREANTAL TRH TREATMENT. † 979

Since 1989 TRH plus glucocorticoids combination has been studying in humans. Aim: to evaluate the incidence and severity of RDS and chronic lung disease (CLD) after prenatal TRH plus betamethasone treatment. Hormonal studies included free T3 (FT3) [nd/dl], free T4 (FT4) [ng/dl], TSH[μU/ml] and prolactin (PRL) [ng/ml]. The correlation between RDS and thyroid function and PRL was analysed. Methods: study group (TRH+B) 58 newborns with mean 31.9 wga and mean birth weight 1795g. Control group(B) 68 neonates of 31.5 mean wga and 1714g mean birthweight. Hormonal analysis was performed on cord blood, and day 1 and 7 of life. For statistical analysis, Statistica 4.5 for Windows was used. Results: 1) no statistical differences in mean TSH level was found in any sample between study and control group (10.70 vs 10.62 in cord; 7.34 vs 5.48 after day 1; 3.33 vs 4.38 after day 7). 2) FT3 concentration did not differ in particular samples for TRH +B and B group (0.22 vs 0.25 in cord; 0.33 vs 0.31 after day 1 and 0.34 vs 0.33 after day 7). 3) There was statistically significant difference in FT4 level, in cord blood (1.26 in TRH +B vs 1.18 in B group; p< 0.05), but not in other samples (1.64 v. 1.63 after day 1 and 1.42 vs 1.28 after day 7). 4) PRL level was similar in study and control goup in each succeeding samples (97.07 vs 112.59; 108.88 vs 93.27; 73.64 vs 72.58). RDS and thyroid function. 5) Mean TSH level in cord blood was higher in group with RDS (12.90 vs 9.28). On day 1 it was lower in RDS group (5.21 vs 7.27; p < 0.01). On day 7 there was no statistical difference between both groups (4.28 in RDS and 2.85 in control group). 6) FT3 level was lower in RDS than in control group in each sample (0.23 vs 0.26; 0.24 * vs 0.39*; 0.31 vs 0.37; *p <0.001). 7) FT4 concentration was slightly higher in RDS group in cord blood (1.24 vs 1.19). On day 1 and 7 FT4 level was higher in control group (1.68 vs 1.59 and 1.44 vs 1.26). 8) Prolactin level was lower in RDS group in each following samples: cord blood; 99.82 vs 113.62; day 1: 79.55 vs 116.60, p<0.01; and day 7: 66.43 vs 81.02. Conclusions: fetal pituitary-thyroid axis is sensitive to exogenous TRH. Low thyroid hormones concentration ininfants with RDS may have an important role in protectig sick neonate from higher oxygen consumption in situations when it's delivery to organs and tissues is imparied. The rate of T4 to T3 conversion is low in these situations, with overproduction of rT3. We suggest that hormonal disturbances in infants with RDS are transient and contribute to a low T3 syndrome.

Incidence and prediction of bronchopulmonary dysplasia in a cohort of premature infants.

A prospective study on the incidence of bronchopulmonary dysplasia (BPD) in premature infants is reported. A cohort of premature infants with gestational ages < or = 32 weeks, treated during 1989, was followed for one year. Of a total study population of 117 infants, 23 (19.6%) developed BPD, defined as oxygen dependence at 28 postnatal days. However, only 15 infants (12.8%) needed supplementary oxygen at the age of 36 gestational weeks and 5 infants (4.2%) needed supplementary oxygen periodically at one year of age. BPD was found to account for a significant part of both the total and late mortality in the cohort. Measurements of pulmonary mechanics were performed at 3 +/- 1 and 12(13) +/- 1 days of life in a subgroup of 26 infants with RDS who required assisted ventilation for 4 days or longer. No significant difference in lung compliance or resistance could be found during the first examination between infants who later developed BPD and infants with RDS only. At the second examination, infants who later developed BPD had significantly lower lung compliance (0.48 +/- 0.23 ml/cmH2O) than infants in the RDS group (1.50 +/- 0.72 ml/cmH2O) (p < 0.001). Measurements of pulmonary mechanics could be of importance for early prediction of infants at risk of BPD.

Shunts in Patients With Respiratory Distress Syndrome

In Reply.— We agree with Dr Evans that bidirectional ductal shunting is more common than net right-to-left ductal shunting in premature neonates with severe RDS and persistent pulmonary hypertension. Our conclusion that large right-to-left shunts via the ductus are common findings in these cases was not intended to exclude the presence of concomitant left-to-right shunting. In our study population the incidence of right-to-left ductal shunting at 12 and 24 hours of age was 86% and 94% in premature neonates with fatal RDS, 39% and 34% in the severe RDS group, 4% and 0% in the no/mild RDS group, and 6% and 0% in the full-term neonates without RDS.

Plasma endotoxin levels and functions of peripheral granulocytes in surgical patients with respiratory distress syndrome.

Plasma endotoxin levels and granulocyte functions (chemiluminescence and chemotaxis) were determined in fifty-two patients with postoperative sepsis. Seventeen had concurrent respiratory distress syndrome (RDS group) and the remaining thirty-five were free of the syndrome (non-RDS group). The plasma endotoxin concentrations were higher in the RDS group than in the non-RDS group (p less than 0.001). All nine patients with particularly high levels (greater than 80 pg) belonged to the RDS group. We noted a positive correlation in chemiluminescence (p less than 0.001, r = 0.67) and a negative correlation in chemotactic activity (p less than 0.001, r = 0.69). To determine whether endotoxin alters normal granulocyte functions in vitro, healthy granulocytes were treated by the endotoxin (E. coli 0111:B4). There was an increase in chemiluminescence and a decrease in chemotactic activity, as observed in vivo. Furthermore, normal granulocytes chemiluminescence was increased by pretreatment of RDS plasma showing high endotoxin levels in vitro (n = 4, p less than 0.05). Thus, endotoxin in the plasma probably plays an important role in marked changes in peripheral granulocyte functions in patients with respiratory distress syndrome.

447 THE EFFECT OF POST-NATAL AGE ON THE RESPONSE OF THE PITUTITARY-THYROID AXIS TO THYROTROPIN RELEASING HORMONE

Transient hypothyroxinemia is a common problem in the preterm infant. The response of the pituitary-thyroid (P-T) axis to exogenous thyrotropin releasing hormone (TRH) infusion has been used to confirm the euthyroid state of these preterm infants. The purpose of this study was to define the effect of post-natal age on the response of the P-T to TRH infusion. Eight preterm infants with RDS (Group I) and 10 preterm infants without RDS (Group II) received 20 mcg/kg TRH IV on days 3 and 14 of life. The mean birth weights, gestational age and Apgar scores were similar in both groups. The pattern of the serum thyroid stimulating hormone (TSH) response to TRH was similar in both groups on both days. In each group, the mean serum TSH level prior to TRH infusion was similar at day 3 and day 14. The mean serum TSH level was significantly elevated by 30 minutes (m) and declining by 180 m. At 30 and 180 m, the mean serum TSH level was significantly higher at day 3 compared to day 14. Compared to pre-infusion of TRH values, the mean serum thyroxine (T4) and triiodothyronine T3) levels were significantly increased on day 3 at 180 m in both groups. There were no other significant differences in mean serum T4 and T3 levels in either group at any other time.Conclusions: 1) In the preterm infant with or without RDS, the serum TSH response following infusion of TRH is significantly different at day 3 compared to day 14 of life; 2) the thyroid gland response is similar at 3 and 14 days.